Is it permissible to say, "O Allah, Lord of this perfect call and the prayer to be offered, grant our master Muhammad the Wasilah and the Fadilah and the high rank which You have promised him, for You never break Your promise" after the Iqama, or should "for You never break Your promise" not be mentioned?

It is prescribed for a Muslim, upon hearing the call to prayer (adhan), to repeat what the muezzin says, and then to recite the prescribed supplications (adhkar). The Prophet, peace and blessings be upon him, commanded this. This applies both after the adhan and after the iqama (the second call to prayer). There is no harm in limiting oneself to the narration found in Al-Bukhari, or adding to it "Indeed, You do not break Your promise," as it is present in another narration by Al-Bayhaqi. However, the addition of "the exalted rank" has not been mentioned in any of the narrations. Therefore, one should restrict oneself to what has been authentically reported from the Messenger of Allah, peace and blessings be upon him.